Pretty simple question, but it's so hard to find an answer!

I'm working with a client (I'm a web designer) and we're using Zen Cart (obviously). I have a template created and coded for him. However, I need to know how to split it up into Zen Cart-iness.

It's a one page XHTML file with a stylesheet. I have everything defined, but not broken up, as in the sidebar is in the same page with the header and the body.

So what files do I need to edit exactly?

From what I see, I need like a sidebar tpl, a header tpl, etc.

The last cart I used to skin there were just variables to implement boxes or whatnot.

Am I coming off clear? Basically, I need to turn a coded site into a Zen Cart template. And have no idea what to do. Google was NOT my friend...